if (bytesLeft == -1L || constructed) {
      throw ProtocolException("constructed strings not supported for DER")
    }
    return source.readUtf8(bytesLeft)
  }

  fun readObjectIdentifier(): String {
    val result = Buffer()
    val dot = '.'.code.toByte().toInt()
    when (val xy = readVariableLengthLong()) {
      in 0L until 40L -> {
        result.writeDecimalLong(0)

      tagClass = DerHeader.TAG_CLASS_UNIVERSAL,
      tag = 6L,
      codec =
        object : BasicDerAdapter.Codec<String> {
          override fun decode(reader: DerReader): String = reader.readObjectIdentifier()

          override fun encode(
            writer: DerWriter,
            value: String,
          ) = writer.writeObjectIdentifier(value)
        },
    )

  val UTF8_STRING =

      assertThat(header.tag).isEqualTo(6L)
      assertThat(header.tagClass).isEqualTo(DerHeader.TAG_CLASS_UNIVERSAL)
      assertThat(header.length).isEqualTo(3L)
      assertThat(derReader.readObjectIdentifier()).isEqualTo("2.999.3")
    }

    assertThat(derReader.hasNext()).isFalse()
  }

  @Test fun `encode object identifier without adapter`() {
    val buffer = Buffer()